package org.madore.damlengine;

import java.util.MissingResourceException;
import java.util.regex.Pattern;
import java.util.regex.Matcher;
import java.util.Properties;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.BufferedReader;
import java.io.PrintStream;
import java.io.IOException;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.Files;
import java.nio.file.StandardCopyOption;
import java.nio.file.NoSuchFileException;
import javax.xml.XMLConstants;
import javax.xml.namespace.NamespaceContext;
import org.w3c.dom.*;
import org.w3c.dom.ls.DOMImplementationLS;
import org.w3c.dom.ls.LSParser;
import org.w3c.dom.ls.LSInput;
import org.apache.xerces.dom.DOMImplementationSourceImpl;
import org.apache.xerces.xni.parser.XMLErrorHandler;
import org.apache.xerces.xni.parser.XMLParseException;

public final class DamlEngine {

    // NOTE TO SELF: install the w3c-dtd-xhtml Debian package to have
    // a local copy of the various standard DTDs of HTML and not
    // download them from the W3C's web site.

    public static final String XMLNS_NS = XMLConstants.XMLNS_ATTRIBUTE_NS_URI;
    public static final String XML_NS = XMLConstants.XML_NS_URI;
    public static final String XHTML_NS = "http://www.w3.org/1999/xhtml";
    public static final String DAML_NS = "http://www.madore.org/~david/NS/daml/";
    public static final String RDF_NS = "http://www.w3.org/1999/02/22-rdf-syntax-ns#";
    public static final String RSS10_NS = "http://purl.org/rss/1.0/";
    public static final String DUBLINCORE_NS = "http://purl.org/dc/elements/1.1/";
    public static final String SYNDICATION_NS = "http://purl.org/rss/1.0/modules/syndication/";

    public static final class DamlNSMapping implements NamespaceContext {
	// This is used for XPath resolution (_not_ for parsing the document).
	public String getNamespaceURI(String prefix) {
	    if ( prefix == null )
		throw new IllegalArgumentException("getNamespaceURI() called with null prefix");
	    else if ( prefix.equals("") )
		return XHTML_NS;
	    else if ( prefix.equals("d") )
		return DAML_NS;
	    else if ( prefix.equals("xml") )
		return XML_NS;
	    else if ( prefix.equals("xmlns") )
		return XMLConstants.XMLNS_ATTRIBUTE_NS_URI;
	    else
		return XMLConstants.NULL_NS_URI;
	}
	public String getPrefix(String uri) {
	    throw new UnsupportedOperationException("getPrefix() not implemented");
	}
	public java.util.Iterator<String> getPrefixes(String uri) {
	    throw new UnsupportedOperationException("getPrefixes() not implemented");
	}
    }

    public static final class SelectiveErrorHandler implements XMLErrorHandler {
    	public void warning(String domain, String key, XMLParseException exc) {
    	    System.err.println("warning: line "+exc.getLineNumber()
			       +": "+exc.getMessage());
    	}
    	public void error(String domain, String key, XMLParseException exc) {
	    if ( domain.equals("http://www.w3.org/TR/1998/REC-xml-19980210")
		 && key.equals("MSG_ELEMENT_NOT_DECLARED") )
		return;
    	    System.err.println("error: line "+exc.getLineNumber()
			       +": "+exc.getMessage());
    	}
    	public void fatalError(String domain, String key, XMLParseException exc) {
    	    System.err.println("fatal error: line "+exc.getLineNumber()
			       +": "+exc.getMessage());
    	    throw exc;
    	}
    }

    public static final class IncantDOM {
	static ThreadLocal<DOMImplementation> pdomi
	    = new ThreadLocal<DOMImplementation>();
	public static DOMImplementation getDOMI() {
	    DOMImplementation domi = pdomi.get();
	    if ( domi == null ) {
		DOMImplementationSource source
		    = new DOMImplementationSourceImpl();
		domi = source.getDOMImplementation("XML 3.0 Core 3.0 LS 3.0");
		if ( domi == null )
		    throw new MissingResourceException("failed to obtain DOM implementation",
						       "org.w3c.dom.ls.DOMImplementationLS", "");
		pdomi.set(domi);
	    }
	    return domi;
	}
    }

    private DamlEngine() { // Forbid instantiation
	throw new AssertionError("DamlEngine cannot be instantiated");
    }

    public static class RootTodo extends TodoItem {
	public RootTodo(Context ctx) {
	    super(ctx, null);
	}
	public void handle() {
	    TodoItem it
		= TodoElement.getTodoElement(ctx.doc.getDocumentElement(),
					     ctx, this);
	    this.ownerDeque.registerAtEnd(it);
	}
    }

    public static void processDocument(Document doc,
				       Context.WeblogSelectionContext wsc,
				       Context.DynamicContext dc) {
	TodoDeque todoDeque = new TodoDeque();
	Context ctx = new Context(doc);
	ctx.wsc = wsc;
	ctx.dc = dc;
	todoDeque.registerAtEnd(new RootTodo(ctx));
	todoDeque.dispatchLoop();
    }

    public static void processDocument(Document doc,
				       Context.WeblogSelectionContext wsc) {
	processDocument(doc, wsc, null);
    }

    public static void processDocument(Document doc) {
	processDocument(doc, null, null);
    }

    public static void fullProcess(InputStream in, OutputStream out,
				   Context.WeblogSelectionContext wsc,
				   Context.DynamicContext dc)
	throws Exception {

	final DOMImplementationLS domils
	    = (DOMImplementationLS)(IncantDOM.getDOMI());
	LSParser par
	    = domils.createLSParser(DOMImplementationLS.MODE_SYNCHRONOUS, null);
	par.getDomConfig().setParameter("resource-resolver", new Resolver());
	par.getDomConfig().setParameter("http://xml.org/sax/features/validation", true);
	par.getDomConfig().setParameter("http://xml.org/sax/features/namespaces", true);
	par.getDomConfig().setParameter("http://apache.org/xml/properties/internal/error-handler", new SelectiveErrorHandler());
	LSInput input = domils.createLSInput();
	input.setByteStream(in);
	Document doc = par.parse(input);
	processDocument(doc, wsc, dc);
	doc.normalizeDocument();
	Unparser unparser
	    = new Unparser(doc, new OutputStreamWriter(out, "UTF-8"),
			   "html");
	unparser.unparse();

    }

    public static void fullProcess(InputStream in, OutputStream out,
				   Context.WeblogSelectionContext wsc)
	throws Exception {
	fullProcess(in, out, wsc, null);
    }

    public static void fullProcess(InputStream in, OutputStream out)
	throws Exception {
	fullProcess(in, out, null, null);
    }

    public static boolean runAsServlet = false;
    public static Properties appProps;
    public static Path basePath;
    public static Path templatePath;

    private interface Processor {
	public void process(OutputStream out) throws Exception;
    }
    private static void processWithTemp(Processor p, String outf)
	throws Exception {
	Path tempPath = (outf != null) ? Paths.get(outf+".temp") : null;
	OutputStream out = (tempPath != null)
	    ? Files.newOutputStream(tempPath)
	    : System.out;
	try {
	    p.process(out);
	    if ( tempPath != null ) {
		out.close();
		Files.move(tempPath, Paths.get(outf),
			   StandardCopyOption.REPLACE_EXISTING,
			   StandardCopyOption.ATOMIC_MOVE);
	    }
	} finally {
	    try {
		if (tempPath != null )
		    Files.deleteIfExists(tempPath);
	    } catch ( Exception e ) { }
	}
    }

    public static void main(String[] args)
	throws Exception {

	appProps = new Properties();
	Path appPropsFile = null;
	if ( System.getenv("DAMLENGINE_PROPERTIES_PATH") != null )
	    appPropsFile = Paths.get(System.getenv("DAMLENGINE_PROPERTIES_PATH"));
	if ( appPropsFile == null ) {
	    if ( System.getProperty("user.home") != null )
		appPropsFile = Paths.get(System.getProperty("user.home"),"damlengine.properties");
	    else
		appPropsFile = Paths.get("damlengine.properties");
	}
	try {
	    appProps.load(Files.newInputStream(appPropsFile));
	} catch (NoSuchFileException e) { }

	basePath = null;
	if ( System.getenv("DAMLENGINE_BASE_PATH") != null )
	    basePath = Paths.get(System.getenv("DAMLENGINE_BASE_PATH"));
	if ( basePath == null && appProps.getProperty("base_path") != null )
	    basePath = Paths.get(appProps.getProperty("base_path"));
	if ( basePath == null ) {
	    basePath = Paths.get(".");
	    System.err.println("warning: using working directory as base path");
	}

	templatePath = null;
	if ( System.getenv("DAMLENGINE_TEMPLATE_PATH") != null )
	    templatePath = Paths.get(System.getenv("DAMLENGINE_TEMPLATE_PATH"));
	if ( templatePath == null && appProps.getProperty("template_path") != null )
	    templatePath = Paths.get(appProps.getProperty("template_path"));
	if ( templatePath == null ) {
	    templatePath = basePath.resolve("templates");
	    System.err.println("warning: using "+templatePath.toString()+" as template path");
	}

	BufferedReader buf = new BufferedReader(new InputStreamReader(System.in, "UTF-8"));
	String line;
	Matcher matcher;

	while ( ( line = buf.readLine() ) != null ) {
	    if ( Pattern.matches("^\\s+$", line) )
		continue;
	    System.err.println(line);
	    if ( (matcher=Pattern.compile("process\\s+(\\S+)(?:\\s+\\>\\s*(\\S+))?\\s*").matcher(line)).matches() ) {
		final String inf = matcher.group(1);
		final String outf = matcher.group(2);
		final InputStream in = Files.newInputStream(basePath.resolve(inf));
		processWithTemp(new Processor() {
			public void process(OutputStream out) throws Exception {
			    fullProcess(in, out);
			}
		    }, outf);
	    } else if ( (matcher=Pattern.compile("process-weblog-month\\s+(\\d{4})\\-(\\d{2})(?:\\s+\\>\\s*(\\S+))?\\s*").matcher(line)).matches() ) {
		final String year = matcher.group(1);
		final String month = matcher.group(2);
		final String outf = matcher.group(3);
		processWithTemp(new Processor() {
			public void process(OutputStream out) throws Exception {
			    WeblogSelect.fullProcess(new Context.WeblogMonthSelectionContext(year,month),
						     out);
			}
		    }, outf);
	    } else if ( (matcher=Pattern.compile("process-weblog-cat\\s+([a-z0-9\\-]+)(?:\\s+\\>\\s*(\\S+))?\\s*").matcher(line)).matches() ) {
		final String code = matcher.group(1);
		final String outf = matcher.group(2);
		processWithTemp(new Processor() {
			public void process(OutputStream out) throws Exception {
			    WeblogSelect.fullProcess(new Context.WeblogCategorySelectionContext(code),
						     out);
			}
		    }, outf);
	    } else if ( (matcher=Pattern.compile("process-weblog-recent\\s+(\\d+)(?:\\s+\\>\\s*(\\S+))?\\s*").matcher(line)).matches() ) {
		final int count = Integer.parseInt(matcher.group(1));
		final String outf = matcher.group(2);
		processWithTemp(new Processor() {
			public void process(OutputStream out) throws Exception {
			    WeblogSelect.fullProcess(new Context.WeblogRecentSelectionContext(count),
						     out);
			}
		    }, outf);
	    } else if ( (matcher=Pattern.compile("process-weblog-single\\s+(\\d+)(?:\\s+\\>\\s*(\\S+))?\\s*").matcher(line)).matches() ) {
		final int number = Integer.parseInt(matcher.group(1));
		final String outf = matcher.group(2);
		processWithTemp(new Processor() {
			public void process(OutputStream out) throws Exception {
			    WeblogSelect.fullProcess(new Context.WeblogSingleSelectionContext(number),
						     out);
			}
		    }, outf);
	    } else if ( (matcher=Pattern.compile("process-weblog-index(?:\\s+\\>\\s*(\\S+))?\\s*").matcher(line)).matches() ) {
		final String outf = matcher.group(1);
		processWithTemp(new Processor() {
			public void process(OutputStream out) throws Exception {
			    WeblogIndexSelect.fullProcess(out);
			}
		    }, outf);
	    } else if ( (matcher=Pattern.compile("process-weblog-rss(?:\\s+\\>\\s*(\\S+))?\\s*").matcher(line)).matches() ) {
		final String outf = matcher.group(1);
		processWithTemp(new Processor() {
			public void process(OutputStream out) throws Exception {
			    WeblogRSS.fullProcess(out);
			}
		    }, outf);
	    } else if ( (matcher=Pattern.compile("populate-weblog\\s+(\\S+)\\s*").matcher(line)).matches() ) {
		final String inf = matcher.group(1);
		final InputStream in = Files.newInputStream(basePath.resolve(inf));
		WeblogPopulate.populate(in);
	    } else if ( (matcher=Pattern.compile("echo\\s+(\\S+)(?:\\s+\\>\\s*(\\S+))?\\s*").matcher(line)).matches() ) {
		final String str = matcher.group(1);
		final String outf = matcher.group(2);
		final OutputStream out = (outf != null)
		    ? Files.newOutputStream(Paths.get(outf))
		    : System.out;
		new PrintStream(out, true).println(str);
		if ( outf != null )
		    out.close();
	    } else {
		throw new IllegalArgumentException("couldn't understand command");
	    }
	}

    }

}